bharrosh@xxxxxxxxxxx wrote on Thu, 31 Jan 2008 22:29 +0200:
> iscsi bidi support at the generic libiscsi level
> - prepare the additional bidi_read rlength header.
> - access the right scsi_in() and/or scsi_out() side of things.
> also for resid.
> - Handle BIDI underflow overflow from target
>
> Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
I see you do this a bit differently than in your previous patch set.
In particular, the residual handling in libiscsi.c. (I'm editing in
a bit more context to the patch below.)
> + if (scsi_bidi_cmnd(sc) &&
> + (rhdr->flags & (ISCSI_FLAG_CMD_BIDI_UNDERFLOW |
> + ISCSI_FLAG_CMD_BIDI_OVERFLOW))) {
> + int res_count = be32_to_cpu(rhdr->bi_residual_count);
> +
> + if (res_count > 0 &&
> + (rhdr->flags & ISCSI_FLAG_CMD_BIDI_OVERFLOW ||
> + res_count <= scsi_in(sc)->length))
> + scsi_in(sc)->resid = res_count;
> + else
> + sc->result =
> + (DID_BAD_TARGET << 16) | rhdr->cmd_status;
> + }
> +
> if (rhdr->flags & (ISCSI_FLAG_CMD_UNDERFLOW |
> ISCSI_FLAG_CMD_OVERFLOW)) {
> int res_count = be32_to_cpu(rhdr->residual_count);
>
> if (res_count > 0 &&
> (rhdr->flags & ISCSI_FLAG_CMD_OVERFLOW ||
> res_count <= scsi_bufflen(sc)))
> + /* write side for bidi or uni-io set_resid */
> scsi_set_resid(sc, res_count);
> else
> sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
> } else if (rhdr->flags & (ISCSI_FLAG_CMD_BIDI_UNDERFLOW |
> ISCSI_FLAG_CMD_BIDI_OVERFLOW))
> sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
I haven't tested this, but, consider a bidi command that results in
an overflow on the read part, and no overflow on the write part.
E.g., the user supplied a data-in buffer that wasn't big enough to
hold the returned data from the target, but the data-out buffer was
just right.
Then this code will set scsi_in(sc)->resid properly, informing the
caller that there were extra bytes that were not transferred. But
the "else" clause at the bottom will also set sc->result to be bad.
I don't think we want this.
Your earlier patch got rid of the second bidi_overflow handler and
just did all the logic for both bidi and non-bidi cases in a single
if clause. Seemed better.
-- Pete
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